Tehran University of Medical Sciences Iranian Journal of Allergy, Asthma and Immunology 1735-1502 25 2 2026 02 01 251 263 Tao Liu Department of Respiration, The 80th Group Army Hospital of People’s Liberation Army, Weifang, China Na Zhang Department of Respiration, The 80th Group Army Hospital of People’s Liberation Army, Weifang, China Xin Shu Department of Dermatology, The Third Medical Center of Chinese PLA General Hospital, Beijing, China Xiaoxuan Hu Department of Pulmonary and Critical Care Medicine, Weifang No. 2 People’s Hospital, Weifang, China AND Institute of Toxicology and Pharmacology, Academy of Military Medical Sciences, Beijing, China Jingtong Li Department of Respiration, The 80th Group Army Hospital of People’s Liberation Army, Weifang, China Yuxu Zhong Institute of Toxicology and Pharmacology, Academy of Military Medical Sciences, Beijing, China Jinyuan Tang Department of Respiration, The 80th Group Army Hospital of People’s Liberation Army, Weifang, China Xiao-ji Zhu Department of Respiration, The 80th Group Army Hospital of People’s Liberation Army, Weifang, China 2025 04 06 2025 07 25 Sulfur mustard (SM) is a potent chemical warfare agent that causes severe cutaneous, ocular, and pulmonary injuries, with respiratory tract damage being the most life-threatening. Despite its well-documented toxicity, the cellular mechanisms driving SM-induced apoptosis remain poorly understood. This study seeks to elucidate the apoptotic pathways involved in SM-induced pulmonary injury using a rat model. We induced acute lung injury through two delivery methods: intraperitoneal injection (8 mg/kg) and intratracheal instillation (2 mg/kg) of SM, with both doses representing 1 LD50. We assessed apoptosis-related proteins and gene expression through TUNEL staining, immunohistochemistry, and quantitative real-time PCR analyses. Intraperitoneal administration of SM resulted in significantly elevated expression of apoptotic markers including annexin A1, annexin A2, cytochrome C, caspase-12, and JNK3, in alveolar epithelial cells compared to intratracheal delivery. Both TUNEL assays and immunohistochemical staining confirmed these findings. These results indicate that intraperitoneal SM exposure triggers more severe apoptotic responses in alveolar epithelial cells than intratracheal exposure at equivalent doses. These findings demonstrate that intraperitoneal models can effectively identify apoptosis-related molecular targets suitable for therapeutic development. https://ijaai.tums.ac.ir/index.php/ijaai/article/view/4408 https://ijaai.tums.ac.ir/index.php/ijaai/article/download/4408/2235